What you'll find here is a cross between fluffy expansion on the settings that I enjoy and the crunchy mechanics of the various rule systems. Game mechanics will cover anything from classes, races, feats, and/or skills. Check how an article is tagged to see if it's for the system you're looking for. It might not be, but can hopefully be adapted easily.

Before The Fall, advanced prosthetics were used for many reasons - from military to hard labor. While the technology to manufacture advanced robotic limbs is extremely limited, as is anyone with the knowledge to properly attach and maintain the cybernetic links with the host body, there are still those that find the risk worth the rewards. Some simply undergo augmentation to help their community (either through increased labor capabilities or improved combat ability) while others see it as little more than granted power over unenhanced.

The Cyborg Advanced Class comes with a unique array of perks and complications, granting these augmented creatures abilities beyond those around them. Perks and Complications represents the  sacrifice the individual has made to acquire enhanced strength or abilities. These are passive and will always be available unless the augmentation is removed.

Sebekans are brutish, reptilian creatures with thick limbs and an elongated snout. Their facial structure makes it difficult to pronounce many words common on Earth, giving them the appearance of low intelligence. On the contrary, Sebekans are highly intelligent strategists, with a keen intellect and affinity for military strategy. 

If you're not a fan of Palladium's answer for every elder evil (alien intelligence), then this might be right up your alley. I created an alternate set of vampire rules and abilities that took into account the creatures age and generally left the concept of alien intelligences out of the mix entirely. These were specifically created with Rifts in mind, but should translate well to any of their other settings.

Hoots get their name not from any sound they make, but from the close facial resemblance to Earth owls. Hoots are a humanoid avian race, incapable of flight. They are believed to originate from a breach in what was once Northern Colorado, and have spread west into the rugged mountains. Their upper body is covered in feathers, allowing them to endure colder temperatures with greater ease than many humans.